Graduated level



Sept. 30, 1952 A. F. GUBRUD 'GRADUATED LEVEL Filed Feb. l 1950 INVENTOR.`

JPurui S .NWMTIMNWIMI Patented Sept. 30, 1952 UNITED STATES PATENT OFFICE GRADUATED LEVEL Adolph P. Gubrua, Hudson, s. Dak. Application February 1,1950, Serial No. 141,742

1 Claim. 1

This invention relates to spirit levels.

An object of this invention is to provide a spirit level embodying a closed circulating path for the liquid contained therein, and means in the path whereby expansion or contraction of the liquid will not affect the operation of the device.

Another object of this invention is to provide a spirit level in which the expansion or contraction of the liquid therein will have no effect on the size of the bubble.

A further object of this invention is to provide a spirit level which includes graduations along the path of the bubble so that the degree or variation from the horizontal can be readily determined.

With the above and other objects in view, my invention consists in the arrangement, combination'and details of construction disclosed in the drawings and specification, and then more particularly pointed out in the appended claim.

In the drawing:

Figure 1 is a plan View of a spirit level constructed according to an embodiment of this invention.

Figure 2 is a sectional view partly broken away taken substantially on the line 2--2 of Figure 1..

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a fragmentary sectional view taken on the line 4-4 of Figure 1.

Figure 5 is a fragmentary sectional view taken on the line 5-5 of Figure 1.

Referring to the drawing, the numeral I designates generally an elongated flat body formed with a horizontally disposed lower side II and a convex upper side I2. The body ID includes a plate I3 which is secured in face abutting relation thereto by fastening members I4. One side of the body IIJ is formed with an upper longitudinally curved channel I and a lower oppositely curved channel I6. The two channels I5 and I6 are connected together at their opposite ends by end channels I1. A longitudinally bent glass tube I8 is seated in the upper channel I5, and a lower longitudinally bent tube I9 is seated in the lower channel I6. The two tubes I8 and I9 are connected together at the opposite ends thereof by connecting members and are iilled with a suitable expansible liquid, such as glycerine thinned by alcohol except for an air bubble 23.

Lower tube I9 is divided at a central point and its ends extend into receiving tubes 2| which comprise part of a thermo-responsive wafershaped metal housing or reservoir which expands or contracts in accordance with temperature changes. Housing 2l is loosely seated in a ciri cular opening in body I0, the relatively loose seating permitting housing 2l to expand or contract under temperature variations coincidentally with the level liquid so as to prevent exploding of the glass tube I8 and to provide for the maintaining of a single bubble 23 within the tube I8. By providing the lower tube I9 in an upward curvature and the upper tube I8 in a downward turned over with the straight lower edge I I uppermost, the bubble will pass along the length of the tube I8 and may enter the lower tube I9 through one of the connecting members 20.

When the level is lying with thetube I8 uppermost the bubble will return to the upper tube I8 passing along the length of the lower tube I9 and then moving through one of the connectors 2U into the upper tube I8. The convex upper side I2 of the body I0 is formed with oppositely extending graduations 24 which extend from a center indication 25. The graduations 24 are provided so that the user of the level will be able to determine from the position of the bubble 23 the exact grade or inclination of the part with which the level is engaged. The metal wall construction of the wafer shaped thermo-responsive housing 2I is of a heat responsive characteristic substantially the same as the expansion or contraction factor of the liquid within the housing 2l and within the two tubes I8 and I9. In this manner when the liquid is subjected to relatively high heat, housing 2I will expand proportionate to the increase in temperature, thereby providing additional reservoir capacity for the expanded liquid. In like manner, if the device is subjected to cold which would contract the liquid, housing 2l will also contract in proportion to the temperature of the atmosphere and the contraction factor of the liquid.

What is claimed is: A spirit level comprising an elongated body formed with upper and lower longitudinally curved channels connected together at the op- ADoLPH P. GUBRUD.

- REFERENCES CITED The following references are of record in the file of this patent:

y UNITED STATES PATENTS Number Name Date 1,669,035 Belleld May 8, 1928V 1,922,997 Widner Aug. 15, 1933 2,019,178 Elsom Oct. 29, 1935 2,059,551 Christensen Nov. 3, 1936 2,221,912 Diggins Nov. 19, 1940 2,389,664 Gianniniv Nov. 2'?, 1945 FOREIGN PATENTS Number Country Date 28,734 Great Britain of 1910 300,826 Germany 1917 354,998

France 1905 

